Capsaicin gel

ABSTRACT

Clear, water-washable, non-greasy gels useful for topical pain relief contain capsaicin, water, alcohol and a carboxypoly-methylene emulsifier. A method of preparing the gels is disclosed.

FIELD OF THE INVENTION

The present application relates to pharmaceutical compositions. Moreparticularly, it relates to gels containing capsaicin.

BACKGROUND OF THE INVENTION

Many over the counter (o-t-c) products used to relieve deep seated painby topical application contain irritants and relieve pain by acounterirritant action rather than by a direct analgesic effect. Whensuch irritant containing products are applied locally to the intact skinin proper concentration to induce hyperemia and redness withoutblistering, they result in a feeling of warmth which may be followed byrelief of pain.

Irritants have been used most successfully in treating neuralgias,rheumatoid arthritis, bursitis, myositis and integumental pain.

Capsicum is an oleoresin obtained by extracting cayenne pepper withether. It and its active ingredient, capsaicin, have been used for manyyears as irritants in o-t-c compositions intended for pain reliefincluding such well known lotions as HEET, OMEGA OIL and SLOAN'SLINIMENT. In addition, the topical analgesic cream ZOSTRIX (supplied byGen Derm Corporation of Northbrook, Illinois) contains capsaicin 0.025%w/w in a petrolatum containing cream.

The currently available products containing capsicum or capsaicin areuseful and acceptable for many purposes. However, there are applicationsin which it would be advantageous to have a clear, water-washable,non-greasy, capsaicin containing gel, and no such gels are currentlyavailable.

SUMMARY OF THE PRESENT INVENTION

It is an object of the present invention to disclose clear,water-washable, non-greasy gels containing capsaicin and a method ofmaking such gels.

The gels of the present invention are clear, water-washable, non-greasygels which consist essentially of capsaicin, alcohol, water, and aneffective amount of carboxypolymethylene emulsifying agent to form a gelwith the water and the alcohol. The gel also may contain a neutralizingagent for the carboxypolymethylene, a sequestering agent andpreservatives and stabilizers.

The preferred gel contains by weight about 0.025% to about 0.075% ofcapsaicin; about 0.5% to about 2% of a carboxypolymethylene; about 30%to about 45% of ethyl alcohol and about 55% to about 70% of water. Thepreferred gel is clear, water-washable, cool to the touch, non-greasy,and it has spread-ability. It also differs from prior art capsaicincontaining creams and ointments because it contains the capsaicin insolution as opposed to in suspension and it contains no oil orpetroleum.

The method of preparing the gels of the present invention comprisesdissolving the capsaicin in alcohol, adding the carboxypolymethylene toform a dispersion and then adding the water and blending the mixture toform the gel.

The foregoing and other objects and advantages of the gels of thepresent invention will be apparent to those skilled in the art from thedescription which follows:

DESCRIPTION OF THE PREFERRED EMBODIMENTS

The preferred gels have the following formula:

    ______________________________________                                        Capsaicin              0.025% to 0.075%                                       Carbopol 1342 or 1382  1.000%                                                 (carboxypolymethylene)                                                        Neutrol TE (tetrahydroxypropyl                                                                       1.500%                                                 ethylenediamine)                                                              Polysorbate 20 (polyoxyethylene (20)                                                                 0.200%                                                 sorbitan monolaurate)                                                         Uvinol MS 40 (2-hydroxy-4-methoxy-                                                                   0.010%                                                 benzophenone-5-sulfonic acid)                                                 Germall II (diazolidinyl urea)                                                                       0.300%                                                 Di Sodium EDTA USP     0.020%                                                 Ethyl Alcohol SDA 40   38.000%                                                Distilled or Ion Exchange Purified                                                                   100.000%                                               Water q. ad.                                                                  ______________________________________                                    

The preferred gels are made adding the capsaicin to the ethyl alcoholand mixing until it dissolved, adding to the resulting solution, theUvinul MS 40, and the Carbopol and mixing until they are evenlydispersed. To the resulting dispersion 90% of the purified water isadded and then mixed. The Di sodium EDTA is then added with mixing untila uniform dispersion is formed. The Polysorbate 20, Germall II andNeutrol TE are dissolved in the remainder of the water. The resultingaqueous solution is then added to the previously prepared uniformdispersion and the two blended to form a gel.

The preferred gel containing 0.025% capsaicin has the following formula:

    ______________________________________                                        Capsaicin          0.025%                                                     Carbopol 1342 or 1382                                                                            1.000%                                                     Neutrol TE         1.500%                                                     Polysorbate 20     0.200%                                                     Uvinul MS 40       0.010%                                                     Germall II         0.300%                                                     Di Sodium EDTA USP 0.020%                                                     Ethyl Alcohol SDA 40                                                                             38.000%                                                    Purified Water     58.945%                                                    ______________________________________                                    

The gels containing the higher concentrations of the capsaicin containthe same percentages of ingredients as the 0.025% gel except that theycontain proportionately less water.

The capsaicin used in the preferred formulations is synthetic capsaicinwhich is the chemical, trans-8-methyl-N-vanillyl-6-nonenamide. It isavailable from Penta Manufacturing of Fairfield, N.J.

The carboxypolymethylene is an emulsifying agent available from B.F.Goodrich, Specialty & Polymers & Chemicals Division, Cleveland, Ohiounder the product name CARBOPOL. Both CARBOPOL 1342 and CARBOPOL 1382can be used. The carboxypolymethylene is a vinyl polymer with activecarboxyl groups. It is described by the manufacturer as being ahydrophobically modified, cross-linked acrylic acid polymer manufacturedby a co-solvent manufacturing technique using a blend of ethyl acetateand cyclohexane solvents.

The tetrahydroxypropyl ethylenediamine is used to neutralize the acidiccarboxyl groups of the carboxypolymethylene. It is available as NEUTROLTE from BASF Corporation of Parsippany, N.J.

The polyoxymethylene (20) sorbitan monolaurate is a surfactant availablefrom ICI Americas Inc. of Wilmington, Del. under the product namePOLYSORBATE 20 (TWEEN).

The 2-hydroxy-4-methoxybenzophenone-5-sulfonic acid is an ultravioletstabilizer. It is available as Uvinul MS 40 from BASF Corporation.

The diazolidinyl urea is an antimicrobial preservative. It is availableas Germall II from Sulton Laboratories, Inc. of Chatham, N.J.

The Di Sodium EDTA is a sequestering agent. It is available commerciallyfrom many sources.

The ethyl alcohol referred for use in the gel formulation is EthylAlcohol SDA 40-2 which is a 190 proof denatured alcohol available fromQuantum of Cincinnati, Ohio. It contains small amounts of water, t-butylalcohol and less than 0.1% of prucine sulfate.

In clinical tests the gels of the present invention were preferred bypatients and doctors over the commercially available creams. The gelswere easy to spread and water-washable. In addition, they appeared to bemore effective than creams containing the same concentration ofcapsaicin.

It will be apparent to those skilled in the art that a number of changesand modifications can be made without departing from the spirit andscope of the present invention. Therefore, it is intended that theinvention only be limited by the claims.

We claim:
 1. A clear, water-soluble, non-greasy gel consistingessentially of the following by weight:(a) about 0.025% to about 0.075%capsaicin; (b) about 0.5% to about 2% of a carboxypolymethyleneemulsifying agent; (c) about 30% to about 45% ethyl alcohol; and (d)about 55% to about 70% water.
 2. A clear, water-soluble, non-greasy gelconsisting essentially of the following by weight:(a) about 0.025% toabout 0.075% capsaicin; (b) about 1% of a carboxypolymethyleneemulsifying agent; (c) about 1.5% of tetralhydroxypropyl ethylenediemineas a neutralizing agent for the carboxypolymethylene; (d) about 0.20% ofdisodium EDTA as a sequestering agent; (e) about 0.30% of diazolidinylurea as an antimicrobial preservative; (f) about 0.20% of a surfactant;(g) about 38% ethyl alcohol; and (h) about 59% water.
 3. A gel of claim2 which also contains an effective amount of an ultraviolet stabilizer.4. A method of preparing a clear, water-soluble, non-greasy capsaicingel of claim 2 which comprises forming a first solution by dissolvingthe capsaicin in the ethyl alcohol, dispersing the carboxypolymethyleneemulsifying agent in the capsaicin/ethyl alcohol, and adding about 90%of the water and the sequestering agent; preparing a second solutioncontaining the neutralizing agent, the antimicrobial agent, thesurfactant and the remainder of the water; and, combining the firstsolution and the second solution to form a gel.